AMORY, Miss. — Most drivers fuel their vehicles with gasoline. Robert Tomey powers his with French fry grease.

The owner of four McDonald's — in Amory, Aberdeen, Houston and Vernon, Ala. — recently converted his Volkswagen Beetle and the company's Ford pickup truck to run on used vegetable oil drained from his fryers.

It's a little messy to pour into the gas tanks and smells a bit like popcorn when leaving the exhaust system, but the fry grease powers his vehicles the same as regular diesel.

And perhaps even better: Tomey once spent more than $350 a week for diesel — he now spends next to nothing.

"I couldn't believe it was that easy," Tomey said while pouring gooey grease into the tank of his silver Beetle. "It's incredible. I want everybody to do this."

Pacing between the Ford and the Beetle parked outside his Amory McDonald's, Tomey envisioned an alliance of Northeast Mississippians running their cars on his grease. If they make the conversion, he said, he'll supply the fuel. He's got enough of it to power 20-30 vehicles annually.

10,000 gallon supply
"I throw away 10,000 gallons of grease every year from all my locations," Tomey said. "I have more than I can use."

Such an alliance is likely, said Steve McMullen, service manager at Aberdeen Ford, which converted Tomey's vehicles.

The conversions worked so well, he said, it'd be puzzling if more people didn't do the same thing.

McMullen and his team installed the converter kit that Tomey bought from a popular online vendor, Greasecar. First they outfitted the Ford. Then, after Tomey saw that it worked, they installed a second kit for the Beetle.

Instead of compromising the integrity of the vehicles, the conversions actually boosted performance, McMullen said.

"The engine runs cooler," he said. "I think it's because the flash point — the ignition point — of that grease is lower than the diesel fuel."

System uses two tanksConverted vehicles using Greasecar have two gas tanks. Drivers pour diesel into the regular tank and vegetable oil into a separate tank. In the Beetle, for example, that tank is in the trunk.

A switch installed in the cab allows drivers to alternate between the two fuel systems. When Tomey starts his Beetle he activates the diesel tank to warm the car and heat the vegetable oil.

"If I didn't heat it in this weather, it'd be too thick to run through the engine," he said from inside his running car. "After it heats up, it gets to the same consistency as the diesel."

At that point, Tomey flipped to the second tank and the car pumped pure vegetable oil into the motor.

"If I filled both tanks with this stuff, I could go 1,500 miles without ever stopping for gas," he said. "I've already gone 600 miles and used only a couple of gallons of diesel."

Purge process a must
Before shutting down the vehicle for a prolonged time, Tomey switches back to the diesel tank to purge the oil from the motor. That prevents vegetable oil from hardening in the fuel lines.

The entire conversion cost about $1,350 per vehicle — $795 for the kit and $550 for the installation. Tomey will recoup that cost in about eight months with the money he'll save on diesel.

But it's not about the money as much as it's about political independence from overseas fuel sources and environmental sustainability, Tomey said.

Vegetable oil doesn't pollute the environment the way diesel fuel does, according to Greasecar. And getting oil from the local McDonald's or other restaurants willing to donate it cuts out Big Oil suppliers that tap the Middle East.

Alternate fuels exist, Tomey said, people just have to look for them. If the current gas crunch has done anything, he said, it's converted a few more vehicles and a few more minds.

"Almost everywhere I go, people are asking me questions about my cars," said Tomey, whose Beetle sports a Greasecar bumper sticker and a license plate that reads "Frybrid."

"They're curious, and that's good."

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